Par Winzell
384 lines
14 KiB
Java
384 lines
14 KiB
Java
//
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// $Id$
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//
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// Depot library - a Java relational persistence library
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// Copyright (C) 2006-2008 Michael Bayne and Pär Winzell
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//
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// This library is free software; you can redistribute it and/or modify it
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// under the terms of the GNU Lesser General Public License as published
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// by the Free Software Foundation; either version 2.1 of the License, or
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// (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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package com.samskivert.depot.impl;
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import java.sql.Connection;
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import java.sql.PreparedStatement;
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import java.sql.ResultSet;
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import java.sql.SQLException;
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import java.util.Collection;
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import java.util.Iterator;
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import java.util.List;
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import java.util.Map;
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import java.util.Set;
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import com.google.common.collect.Lists;
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import com.google.common.collect.Sets;
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import com.google.common.collect.Maps;
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import com.samskivert.jdbc.DatabaseLiaison;
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import com.samskivert.jdbc.JDBCUtil;
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import com.samskivert.depot.DatabaseException;
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import com.samskivert.depot.DepotRepository;
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import com.samskivert.depot.Key;
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import com.samskivert.depot.KeySet;
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import com.samskivert.depot.PersistenceContext;
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import com.samskivert.depot.PersistentRecord;
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import com.samskivert.depot.SimpleCacheKey;
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import com.samskivert.depot.Stats;
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import com.samskivert.depot.clause.FieldOverride;
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import com.samskivert.depot.clause.QueryClause;
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import com.samskivert.depot.clause.SelectClause;
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import com.samskivert.depot.operator.Conditionals.*;
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import static com.samskivert.depot.Log.log;
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/**
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* This class implements the functionality required by {@link DepotRepository#findAll}: fetch
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* a collection of persistent objects using one of two included strategies.
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*/
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public abstract class FindAllQuery<T extends PersistentRecord> extends Query<List<T>>
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{
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/**
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* The two-pass collection query implementation. See {@link DepotRepository#findAll} for
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* details.
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*/
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public static class WithCache<T extends PersistentRecord> extends FindAllQuery<T>
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{
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public WithCache (PersistenceContext ctx, Class<T> type,
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Collection<? extends QueryClause> clauses)
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throws DatabaseException
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{
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super(ctx, type);
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if (_marsh.getComputed() != null) {
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throw new IllegalArgumentException(
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"This algorithm doesn't work on @Computed records.");
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}
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for (QueryClause clause : clauses) {
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if (clause instanceof FieldOverride) {
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throw new IllegalArgumentException(
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"This algorithm doesn't work with FieldOverrides.");
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}
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}
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_select = new SelectClause<T>(_type, _marsh.getPrimaryKeyFields(), clauses);
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_qkey = new SimpleCacheKey(_marsh.getTableName() + "Keys", _select.toString());
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}
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@Override // from Query
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public List<T> getCachedResult (PersistenceContext ctx)
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{
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if (_qkey == null) {
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return null;
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}
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_keys = ctx.<KeySet<T>>cacheLookup(_qkey);
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if (_keys == null) {
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return null;
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}
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_cachedQueries++;
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_fetchKeys = loadFromCache(ctx, _keys, _entities);
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return (_fetchKeys.size() == 0) ? resolve(_keys, _entities) : null;
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}
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// from Query
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public List<T> invoke (PersistenceContext ctx, Connection conn, DatabaseLiaison liaison)
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throws SQLException
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{
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// we want this to remain null if our key set came from the cache
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String stmtString = null;
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// if we didn't find our key set in the cache, load the keys that match
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if (_keys == null) {
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List<Key<T>> keys = Lists.newArrayList();
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SQLBuilder builder = ctx.getSQLBuilder(DepotTypes.getDepotTypes(ctx, _select));
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builder.newQuery(_select);
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PreparedStatement stmt = builder.prepare(conn);
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stmtString = stmt.toString(); // for debugging
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try {
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ResultSet rs = stmt.executeQuery();
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while (rs.next()) {
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keys.add(_marsh.makePrimaryKey(rs));
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}
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} finally {
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JDBCUtil.close(stmt);
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}
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_keys = KeySet.newKeySet(_type, keys);
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_uncachedQueries++;
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if (PersistenceContext.CACHE_DEBUG) {
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log.info("Loaded " + _marsh.getTableName() + " keys", "query", _select,
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"keys", keysToString(_keys), "cacheable", (_qkey != null));
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}
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if (_qkey != null) {
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ctx.cacheStore(_qkey, _keys); // cache the resulting key set
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}
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// and fetch any records we can from the cache
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_fetchKeys = loadFromCache(ctx, _keys, _entities);
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}
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// finally load the rest from the database
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return loadAndResolve(ctx, conn, _keys, _fetchKeys, _entities, stmtString);
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}
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protected SimpleCacheKey _qkey;
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protected SelectClause<T> _select;
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protected KeySet<T> _keys;
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protected Set<Key<T>> _fetchKeys;
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protected Map<Key<T>, T> _entities = Maps.newHashMap();
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}
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/**
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* The two-pass collection query implementation. See {@link DepotRepository#findAll} for
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* details.
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*/
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public static class WithKeys<T extends PersistentRecord> extends FindAllQuery<T>
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{
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public WithKeys (PersistenceContext ctx, Iterable<Key<T>> keys)
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throws DatabaseException
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{
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super(ctx, keys.iterator().next().getPersistentClass());
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_keys = keys;
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}
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@Override // from Query
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public List<T> getCachedResult (PersistenceContext ctx)
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{
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// look up what we can from the cache
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_fetchKeys = loadFromCache(ctx, _keys, _entities);
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// if we found everything, we can just return our result straight away, yay!
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return _fetchKeys.isEmpty() ? resolve(_keys, _entities) : null;
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}
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// from Query
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public List<T> invoke (PersistenceContext ctx, Connection conn, DatabaseLiaison liaison)
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throws SQLException
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{
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return loadAndResolve(ctx, conn, _keys, _fetchKeys, _entities, null);
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}
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protected Iterable<Key<T>> _keys;
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protected Set<Key<T>> _fetchKeys;
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protected Map<Key<T>, T> _entities = Maps.newHashMap();
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}
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/**
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* The single-pass collection query implementation. See {@link DepotRepository#findAll} for
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* details.
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*/
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public static class Explicitly<T extends PersistentRecord> extends FindAllQuery<T>
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{
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public Explicitly (PersistenceContext ctx, Class<T> type,
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Collection<? extends QueryClause> clauses, boolean cachedContents)
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throws DatabaseException
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{
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super(ctx, type);
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_select = new SelectClause<T>(type, _marsh.getFieldNames(), clauses);
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if (cachedContents) {
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_qkey = new SimpleCacheKey(_marsh.getTableName() + "Contents", _select.toString());
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} else {
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_qkey = null;
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}
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}
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@Override // from Query
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public List<T> getCachedResult (PersistenceContext ctx)
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{
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if (_qkey != null) {
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_cachedQueries++;
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return ctx.cacheLookup(_qkey);
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}
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return null;
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}
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// from Query
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public List<T> invoke (PersistenceContext ctx, Connection conn, DatabaseLiaison liaison)
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throws SQLException
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{
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List<T> result = Lists.newArrayList();
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SQLBuilder builder = ctx.getSQLBuilder(DepotTypes.getDepotTypes(ctx, _select));
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builder.newQuery(_select);
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PreparedStatement stmt = builder.prepare(conn);
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try {
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ResultSet rs = stmt.executeQuery();
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while (rs.next()) {
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result.add(_marsh.createObject(rs));
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}
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} finally {
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JDBCUtil.close(stmt);
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}
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_explicitQueries++;
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if (PersistenceContext.CACHE_DEBUG) {
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log.info("Loaded " + _marsh.getTableName(), "query", _select, "rows",
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result.size(), "cacheKey", _qkey);
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}
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if (_qkey != null) {
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ctx.cacheStore(_qkey, result); // cache the entire result set
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}
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return result;
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}
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protected SelectClause<T> _select;
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protected SimpleCacheKey _qkey;
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}
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// from Query
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public void updateStats (Stats stats)
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{
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stats.noteQuery(_cachedQueries, _uncachedQueries, _explicitQueries,
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_cachedRecords, _uncachedRecords);
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}
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protected FindAllQuery (PersistenceContext ctx, Class<T> type)
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throws DatabaseException
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{
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_type = type;
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_marsh = ctx.getMarshaller(type);
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}
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protected Set<Key<T>> loadFromCache (PersistenceContext ctx, Iterable<Key<T>> allKeys,
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Map<Key<T>, T> entities)
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{
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Set<Key<T>> fetchKeys = Sets.newHashSet();
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for (Key<T> key : allKeys) {
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T value = ctx.<T>cacheLookup(key);
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if (value != null) {
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@SuppressWarnings("unchecked") T newValue = (T) value.clone();
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entities.put(key, newValue);
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continue;
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}
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fetchKeys.add(key);
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}
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if (PersistenceContext.CACHE_DEBUG) {
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log.info("Loaded from cache " + _marsh.getTableName(), "count", entities.size());
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}
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_cachedRecords = entities.size();
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_uncachedRecords = fetchKeys.size();
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return fetchKeys;
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}
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protected List<T> resolve (Iterable<Key<T>> allKeys, Map<Key<T>, T> entities)
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{
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List<T> result = Lists.newArrayList();
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for (Key<T> key : allKeys) {
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T value = entities.get(key);
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if (value != null) {
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result.add(value);
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}
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}
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return result;
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}
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protected List<T> loadAndResolve (PersistenceContext ctx, Connection conn,
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Iterable<Key<T>> allKeys, Set<Key<T>> fetchKeys,
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Map<Key<T>, T> entities, String origStmt)
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throws SQLException
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{
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if (PersistenceContext.CACHE_DEBUG && fetchKeys.size() > 0) {
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log.info("Loading " + _marsh.getTableName(), "keys", keysToString(fetchKeys));
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}
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// if we're fetching a huge number of records, we have to do it in multiple queries
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if (fetchKeys.size() > In.MAX_KEYS) {
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int keyCount = fetchKeys.size();
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do {
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Set<Key<T>> keys = Sets.newHashSet();
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Iterator<Key<T>> iter = fetchKeys.iterator();
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for (int ii = 0; ii < Math.min(keyCount, In.MAX_KEYS); ii++) {
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keys.add(iter.next());
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iter.remove();
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}
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keyCount -= keys.size();
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loadRecords(ctx, conn, keys, entities, origStmt);
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} while (keyCount > 0);
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} else if (fetchKeys.size() > 0) {
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loadRecords(ctx, conn, fetchKeys, entities, origStmt);
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}
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return resolve(allKeys, entities);
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}
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protected void loadRecords (PersistenceContext ctx, Connection conn, Set<Key<T>> keys,
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Map<Key<T>, T> entities, String origStmt)
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throws SQLException
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{
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SelectClause<T> select = new SelectClause<T>(
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_type, _marsh.getFieldNames(), KeySet.newKeySet(_type, keys));
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SQLBuilder builder = ctx.getSQLBuilder(DepotTypes.getDepotTypes(ctx, select));
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builder.newQuery(select);
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PreparedStatement stmt = builder.prepare(conn);
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try {
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Set<Key<T>> got = Sets.newHashSet();
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ResultSet rs = stmt.executeQuery();
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int cnt = 0, dups = 0;
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while (rs.next()) {
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T obj = _marsh.createObject(rs);
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Key<T> key = _marsh.getPrimaryKey(obj);
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if (entities.put(key, obj) != null) {
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dups++;
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}
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ctx.cacheStore(key, obj.clone()); // cache our result
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got.add(key);
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cnt++;
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}
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// if we get more results than we planned, or if we're doing a two-phase query and got
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// fewer, then complain
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if (cnt > keys.size() || (origStmt != null && cnt < keys.size())) {
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log.warning("Row count mismatch in second pass", "origQuery", origStmt,
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// we need toString() here or StringUtil will get smart and dump our
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// KeySet using its iterator which results in verbosity
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"wanted", KeySet.newKeySet(_type, keys).toString(),
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"got", KeySet.newKeySet(_type, got).toString(),
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"dups", dups, new Exception());
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}
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if (PersistenceContext.CACHE_DEBUG) {
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log.info("Cached " + _marsh.getTableName(), "count", cnt);
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}
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} finally {
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JDBCUtil.close(stmt);
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}
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}
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protected String keysToString (Iterable<Key<T>> keySet)
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{
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StringBuilder builder = new StringBuilder("(");
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for (Key<T> key : keySet) {
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if (builder.length() > 1) {
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builder.append(", ");
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}
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key.toShortString(builder);
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}
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return builder.append(")").toString();
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}
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protected Class<T> _type;
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protected DepotMarshaller<T> _marsh;
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protected int _cachedQueries, _uncachedQueries, _explicitQueries;
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protected int _cachedRecords, _uncachedRecords;
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}
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